OPEN_CURSORS specifies the maximum number of open cursors (handles to private SQL areas) a session can have at once. You can use this parameter to prevent a session from opening an excessive number of cursors. This parameter also constrains the size of the PL/SQL cursor cache which PL/SQL uses to avoid having to reparse as statements are reexecuted by a user.

It is important to set the value of OPEN_CURSORS high enough to prevent your application from running out of open cursors. The number will vary from one application to another. Assuming that a session does not open the number of cursors specified by OPEN_CURSORS, there is no added overhead to setting this value higher than actually needed.